With the advent of high definition (HD) signals and advanced high resolution display technologies, such as Liquid Crystal Display (LCD) and Plasma, consumers now demand a higher quality of video and audio than ever before. In response to this demand, many content creators, ranging from movie studios to game developers, have begun to produce content that utilizes HD signals. This expansion of HD content has created the need for a simple, yet high-speed communication interface for transmission of digital content between the source and the display device.
The High-Definition Multimedia Interface, commonly known as HDMI, is a digital connection standard that addresses this need. Cables implemented according to the HDMI standard are capable of transmitting both video and audio at high data rates. Given its convenience and high capacity, HDMI has quickly become the preferred connection type for end users, content creators, and equipment manufacturers alike.
As with any system for digital transmission of copyrighted or otherwise regulated data, content protection for HDMI signals is a critical issue. The High-Bandwidth Digital Content Protection (HDCP) system provides one solution for protection of content transmitted over HDMI. In particular, HDCP protects content transmitted over HDMI from a content source, such as a set-top box or high definition disc player (e.g., a BluRay™ disc player), to a display, such as a high-definition television.
In order to properly protect an HDMI link between a source and a receiver (commonly known as a “sink”), the source must first authenticate the sink to verify that the sink is authorized to receive the data. After the source has properly authenticated the sink, the source may begin sending encrypted data over the link. Unfortunately, the entire authentication operation, including pre-authentication processing, is often time consuming, taking in the order of five seconds to complete. In particular, the time required to read Extended Display Identification Data (EDID) from the sink during pre-authentication can take a number of seconds. This is particularly problematic when a user desires to switch between HDMI sources, as the user will experience a noticeable delay with no picture.
In a current implementation for addressing the duration of input switches, the HDMI sink maintains the HDCP authentication for each input, even when the input is not currently selected. Although effective in reducing the duration of input switches, this implementation requires an HDCP engine for each input and therefore requires additional hardware and a large amount of power. These deficiencies increase the cost of implementing this solution for both equipment manufacturers and consumers.
In view of the foregoing, it would be desirable to implement a fast HDMI switching mechanism. More specifically, it would be desirable to implement an HDMI switching mechanism that effectively reduces the duration of input switches, while minimizing costs to manufacturers and consumers. Other desirable aspects will be apparent to those of skill in the art upon reading and understanding the present specification.